Unico 90 is a class A hybrid integrated amplifier with zero feedback, as the most precious valve amplifiers uses only two stages. The heart of the Unico 90 circuit is found in its hybrid structure. All of the gain, and subsequently the "character" of the amp, is determined by the only tube stage made with ECC83 and ECC 81in  particular multiple-parallel-totem-pole.

• Output power: 100+100 W  RMS su 8Ω / 160+160 W  RMS su 4Ω
• Frequency response: -1dB @ 12Hz e 45kHz -3 dB
• Input impedance: 21Kohm // 300pF
• Input sensitivity: 860mV RMS
• Input stage: Pure A class, double triode  totem pole ECC83  and  parallel totem pole ECC81 This single stage due to the particular circuitry is able to amplify the input signal and drive  directly the power stage.
• Output stage: Class AB thermostable, complementary Hexfet (3 pairs for channel)
• Number of stage: 2, This amplifier due to the particular circuitry is realized by only two stages: input stage and output stage, and use only local feedback
• Input: 6 line (3 unbalanced, 2 balanced, 1 “bypass” unbalanced)
• Line Outputs: 1 tape, 1 sub  (volume controlled)
• Output connectors: 4 + 4  bi-wiring
• Global Feedback factor: 0 dB
• THD: < 0.15% @ 1kHz, 1 W
  < 0.5% @ 1kHz, 10 W
• Output resistance: <0.4 ohm, resistive on all audio frequencies
• Power Consumption: 550 W (at max power on 8 ohm)
• Dimensions: 43.5cm x 44 cm x 18 cm h
• Net weight: 20 kg